STI RTQ Series, Instruction Manual, Page: 27 / 44

STI S.r.l. – Via Dei Caravaggi 15, 24040 Levate (BG) – ITALY www.imi-critical.com
Manual 5300, rev. 09 06/2020 – RTQS 23
Warning
Tightening torque must respect the values shown in Table 3 based on the
material stated on note (1).
Table 3
Bolts
Tightening torque
(Nm)
(1)
Bolts
Tightening
torque (Nm)
(1)
M10 40 M30 800
M12 70 M33 1.200
M16 180 M36 1.800
M20 340 M42 3.000
M24 550
M27 700
9.3.3 Replacement of tie rods in field
Failure of tie rod can happen on field due to corrosion or defective material; failure of one tie rod does not
compromise the structural resistance of the cylinder but needs immediate replacement.
In this case it is possible to replace the broken tie rod in field even if the cylinder in under pressure.
Remove with wrench the broken pieces, install a new tie rod and then tighten the nut.
Warning
Tightening torque must respect the values shown in Table 3 based on the
material stated on note (1).
Failed tie rod
Fig. 14 – Cylinder tie rod replacement
(1) The torque values in Table 3 have been
calculated considering the standard tie rods or
bolts made in Carbon Steel according to
ASTM A320 grade L7/ASTM A193 grade B7
for tie rods or bolts and ASTM A194 grade 4
for the nuts. Alternative tie rods or bolts in
Stainless Steel are permitted i.e. ASTM A193
B8M (Class 2 or 2C) for bolts/screws and
ASTM A194 grade 8M for the nuts, provided
that yield strength of tie rods or bolts is not
less than 450 MPa.